According to the National Survey on Oral Health conducted by the National Institute of Dental Research, approximately 42 percent of Americans over 65 years of age and four percent of those 35 to 64 are totally edentulous. Moreover, those over 65 years old who still have some of their teeth have lost an average of 12 of their 28 teeth, and persons aged 55 to 64 have lost an average of nine of their 28 teeth.
When an extracted or otherwise missing tooth is not replaced, atrophy of the jaw bone occurs over time. Consequently, individuals who have been partially or fully edentulous for an extended period of time are left with an atrophic alveolar ridge that can not securely support a full or partial denture or support the placement of a dental implant. Furthermore, the edentulous individual faces a continuing deterioration of aesthetics and a compromised ability to chew leaving the quality of the individual's oral life in an unfortunate state.
FIGS. 1 through 3 illustrate the deteriorating effect of tooth extraction on the alveolar ridge. Turning to FIG. 1, a tooth of a patient, comprised of a crown 10 and root 20, are shown seated in the alveolar (or jaw) bone 30. The buccal and lingual portion of the alveolar bone is surrounded by a layer of tissue known as the gingiva or gum 40. The crown 10 and root 20 are supported by the alveolar ridge or jaw bone 30 and the gingiva 40 which, in the ideal case, is adjacent to the tooth at a level gum line 50 over the underlying bone. Crown height line 60 is shown. When such a tooth or series of teeth become infected or otherwise dentally compromised such that the extraction of the crown 10 and root 20 are required, the root 20 is removed from the alveolar bone 30 by separating the surface of the root 20 from the periodontal membrane 70.
FIG. 2 represents the portion of the alveolar bone 30 shortly after extraction of the crown 10 and root 20. As is shown, the alveolar bleeding clots, such that bleeding ceases and a root extraction socket 90 remains in the alveolar bone 30 in the shape of the extracted root 20.
The buccal and lingual portions of the alveolar bone 30 are composed of bone which has a unique characteristic, i.e., being capable of absorbing the shocks caused by the stress movement of teeth during speech, eating, etc. The removal of a tooth and the resulting absence of frequent use pressure in the area causes the alveolar bone 30 to shrink (i.e., be resorbed) in that area where pressure is no longer applied (the extraction site) with the subsequent loss of 40 to 60 percent (in a 2 to 4 year time) of the alveolar ridge's former height measured at the gum line 50 (i.e., "disuse atrophy"). FIG. 3 shows an extraction site with various degrees of loss of buccal and crestal alveolar bone 30 two years after the extraction of the tooth represented in FIG. 1. The jaw bone continues to atrophy at a bone loss rate of one-half to one percent per year until death of the patient.
Bone graft substitute material has been used to immediately fill a root extraction socket 90 at an extraction site after a root 20 extraction in order to promote bone growth and to avoid the expected bone atrophy, i.e., Ridge Preservation. Bone growth is promoted via the bone graft material's intermixing with the patient's own marrow blood which seeps through the root extraction socket 90. After an appropriate time period to allow alveolar bone regeneration (approximately 12 to 18 months) dense lamina bone forms in the extraction socket area. The patient may then be considered for a denture prosthesis.
The method of applying bone graft material to a newly extracted root site is known. What is desired is a method for installing an implant in a root extraction socket and backfilling the socket area immediately after extraction, i.e., immediate post-extraction implant installation. What is alternately desired is a method for backfilling a root extraction socket with bone graft material immediately after extraction and then delaying installation of an implant in the root extraction socket until bone graft material has promoted sufficient bone growth in the root extraction socket, i.e., delayed post-extraction implant installation.